svndiff.py: add ability to compare before-and-after JSON files, not just raw images

tools/rebaseline.py

 #!/usr/bin/python
 
 '''
 Copyright 2012 Google Inc.
 
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 '''
 
 '''
@@ skipping 83 matching lines @@
     def __init__(self, expectations_root, expectations_filename,
                  actuals_base_url, actuals_filename,
                  tests=None, configs=None, add_new=False):
         self._expectations_root = expectations_root
         self._expectations_filename = expectations_filename
         self._tests = tests
         self._configs = configs
         self._actuals_base_url = actuals_base_url
         self._actuals_filename = actuals_filename
         self._add_new = add_new
-        self._testname_pattern = re.compile('(\S+)_(\S+).png')
+        self._testname_pattern = re.compile(gm_json.IMAGE_FILENAME_PATTERN)
 
     # Returns the full contents of filepath, as a single string.
     # If filepath looks like a URL, try to read it that way instead of as
     # a path on local storage.
     #
     # Raises _InternalException if there is a problem.
     def _GetFileContents(self, filepath):
         if filepath.startswith('http:') or filepath.startswith('https:'):
             try:
                 return urllib2.urlopen(filepath).read()
@@ skipping 182 matching lines @@
             dry_run=args.dry_run,
             json_base_url=args.actuals_base_url,
             json_filename=args.actuals_filename,
             add_new=args.add_new,
             missing_json_is_fatal=missing_json_is_fatal)
     try:
         rebaseliner.RebaselineSubdir(subdir=subdir, builder=builder)
     except BaseException as e:
         print >> sys.stderr, e
         sys.exit(1)